Rigid or soft body dummy legs?
I think you mean you want the children objects (i.e. the legs) to follow the parent in a delayed way like this:



To do so:


Parent the feet to the body.
Under Relations Extras in the Object Settings, check the Slow Parent checkbox and set the Offset to 10.0


This next step is optional, but if you want to prevent the feet from ever getting farther than a few units away from the body, you can add a Limit Distance constraint. Go to the constraints tab, add a Limit Distance constraint, set the distance to something around 4.0 units and set the target to the parent object: